Arthur always knew Merlin had a secret.
Well, not always. When Merlin told him in the market that he could take Arthur apart with less than one blow, he thought he was nuts. On that particular note, he still was.
There was no doubt that Merlin was a goofy, clumsy guy. He got his position in the court by accident, and even then he didn't think someone could fake that. He'd seen many traitors in his life, and prided himself on his ability to spot them. But Merlin was an anomaly.
His secret wasn't dangerous, wasn't suspicious. Arthur doubted it had anything to do with himself at all. But you couldn't deny Merlin had something he was hiding.
The easiest way to tell was how Merlin accompanied him on every patrol, every mission. He had no way of defending himself, and no real reason to go at all. He insisted he needed to protect Arthur, but what could a manservant possibly do.
Another way was that when nobody was looking, a great wisdom and sadness entered Merlin's eyes. As if he had seen more of life than a manservant should. His eyes would fall as Arthur left him to his chores, and Arthur's gaze would linger a moment longer than normal on his servant's hidden side.
Merlin rarely showed himself to Arthur this way. One time was when the dragon attacked Camelot.
"You must be careful. Do not force the battle."
"Yes sire!" Arthur said sarcastically.
"I'm serious."
"I can hear that."
Merlin steadied his breath, and said "Let matters take their course."
Merlin had let the mysterious wisdom he so often shown take place in his voice, and it unnerved Arthur to feel so in the dark. As if Merlin knew something he didn't.
When Morgana took over Camelot, he guided Arthur like nobody else did. He inspired him to take back Camelot, with a wisdom far beyond his years.
"Yesterday, amongst all your gibberish, you said something that - if I didn't know you - I'd be completely fooled into thinking you were…" Arthur was doing his very best not to compliment Merlin.
He looked quizzical. "What?"
"…wise."
Merlin scoffed. "Nah."
Merlin's unquestionable loyalty. He was so loyal to Arthur that he could even joke about it.
"Merlin?"
He grinned. "Nah, I don't really fancy it."
Exasperation crossed Arthur's face at even this most serious of times. "Merlin you don't have a choice."
Merlin stood. Arthur looked at Merlin, just to make sure.
The smile and nod Merlin gave communicated to Arthur everything he needed to know.
It was Merlin who always insisted he was the greatest King of Camelot, and that he would bring unprecedented peace to the lands. Arthur doubted if he was right, it seemed like the violence of sorcery was at an all-time high.
But it was Merlin's encouragement that drove him - unlike anyone else in his presence, even Gwen, he had absolutely no reason to believe that so strongly.
Arthur began to see the secret by the hole it left very quickly.
"Why'd you leave?"
"Things just… changed."
That was possibly the most noncommittal answer Arthur had ever heard.
"How?"
Arthur pushed Merlin with his feet. "Come on, you. Stop pretending to be interesting and tell me."
"I just didn't fit in anymore. I wanted to find somewhere that I did."
Yet another noncommittal answer. Everyone has their own personal tale of angst, but Merlin seemed particularly mysterious.
"Had any luck?"
"Not sure yet."
Arthur wanted his servant to feel at home.
Arthur often wanted to ask Merlin about what he hid.
Merlin stood in his chain mail, the battle armor only making his thin frame seem thinner.
"You ready?" Arthur asked encouragingly.
"My throat's dry," Merlin answered.
Arthur pressed his lips together. "Me too." The impending deaths within Ealdor weighed on both their minds.
"It's been an honor," Arthur said, gripping his arm. It was far enough back that Merlin was gratified to see the prince not acting like a prat, whatever the situation.
"Whatever happens out there today, please don't think any differently of me."
Arthur got a sudden sense of foreboding, but brushed it off as Merlin's fear.
"I won't. It's alright to be scared, Merlin."
Merlin turned to give Arthur a piercing look.
"That's not what I meant."
That unsettled Arthur, but he pushed it aside, like he often did with things he didn't want to deal with.
"What is it?"
He was met with Merlin's pregnant silence.
"If you've got something to say, now's the time to say it."
Arthur tried to look encouragingly at Merlin. He seemed more afraid to tell Arthur whatever it was than he was of the battle itself.
At the time, he thought it was about his friend Will being a sorcerer. But as the years passed and things only got odder with Merlin, he began to think that maybe he wanted to tell Arthur something else.
He could even tell who knew Merlin, knew what it was he was hiding. He could be seen talking with them, going mysteriously silent when anyone came close. Merlin and Lancelot could often be seen speaking in hushed tones when they thought no one was looking. Merlin values Gaius's opinion above everyone else's, above anyone else's.
Arthur may have been a prince, and then a king, but he wasn't the unobservant fool everyone else took him to be.
He had noticed Merlin's silence after the dragon's attack - everyone had been silent with the weight of destruction, but Merlin's seemed tied to something else.
He remembered how Merlin cried after the dragon lord died - It had seemed hopeless for Camelot's safety, but Merlin was not one to get emotional about the deaths of strangers. If anything, Merlin handled the emotional struggles of war better than even some of his knights.
Arthur also worried about Merlin these past few years. He had seemed to become more withdrawn, more stressed. He said less and less to Arthur these days, and became more and more withdrawn.
Whatever past Merlin had, whatever secret he kept, it was killing him.